2. The most important diagnostic studies for this patient include complete blood count (CBC), prothrombin time (PT), and fibrinogen. It is reasonable to obtain a baseline basic metabolic profile (BMP) and creatinine kinase. There is no need for a partial thromboplastin time (PTT) or D-dimer. Routine imaging is also unnecessary. The leading edge of the tenderness and swelling should also be documented every 15–30 minutes. There is no need for circumferential measurements of the affected limb. 3. Initial management for this patient should address the life threats: Airway, breathing and circulation. Parenteral
analgesia is often needed. The affected limb should be elevated. Tetanus immunization to be updated as needed. Prophylactic antibiotics should not be administered. 4. Antivenom should be considered for any of the following: Progressive local findings in which the swelling and tenderness cross a major joint, for example, wrist or ankle; hematologic laboratory abnormalities, including thrombocytopenia, hypofibrinogenemia, or elevated prothrombin time; and systemic toxicity such as hypotension, respiratory distress, objective weakness, or refractory vomiting or diarrhea.
SPIDER BITES
There are two groups of medically significant spiders in the U.S.: widow spiders and recluse spiders. Other spiders, for example, tarantulas, are occasionally implicated in envenomations, and Widow spiders There are five widow spider species native to the U.S. Widow spiders include the southern black widow ( Latrodectus mactans ), western black widow ( L. hesperus ), northern black widow ( L. variolus ), red widow ( L. bishop ), and brown widow ( L. geometricus ). Nearly every state in the continental U.S. has at least one widow species, and many southern states have two or three species. 70 Between 2015 and 2017, there were 4,307 widow spider exposures reported to the AAPCC, an average of 1,436 envenomations annually. 1-3 Children younger than age six were affected in 301 (7%) cases, and 520 (12.1%) victims were younger than age 20. No fatalities were reported, but 26 patients experienced major effects. Most bites occur when someone inadvertently brushes against or nearly crushes the spider. The female spider, which is responsible for envenomation, can be easily identified by characteristic markings. For example, the southern black widow has a very distinctive red hourglass pattern on the ventral aspect of the abdomen. The clinically important constituent in widow spider venom is α -latrotoxin, which causes a massive release of acetylcholine and catecholamines. There are additional venom components that affect insects but do not appear to cause effects in humans. 71 Figure 12. Southern Black Widow (Latrodectus Mactans)
many more species are blamed—by healthcare professionals and laypeople alike—for clinical effects for which they were not responsible.
and ptosis have been reported.82-85 The constellation of facial muscle spasm, blepharospasm, eyelid edema, lacrimation, and risus sardonicus (forced grimace), collectively known as latrodectus facies , may be observed. Laboratory tests and other diagnostic studies should be obtained if the diagnosis is uncertain and to look for complications from the envenomation. Blood tests should include CBC, PT, pregnancy test (when applicable), CK, liver function tests, serum electrolytes, BUN, and creatinine. A urinalysis and an electrocardiogram (ECG) are also recommended. A chest radiograph should be ordered for patients who report dyspnea or chest discomfort. Patients for whom the diagnosis is unclear may also require additional studies. Supportive treatment usually suffices and is frequently the only option, because widow spider antivenom may not be readily accessible. Ensure airway and breathing. Intravenous fluid resuscitation may be necessary when patients have significant diaphoresis and/or vomiting. Provide analgesia with parenteral opioids. Benzodiazepines should be used liberally for muscle relaxation and anxiolysis. Hypertension typically responds to benzodiazepines and opioids. Refractory hypertension should be treated with rapidly acting, titratable medications in patients at risk for myocardial infarction or cerebrovascular accident. Both nicardipine and esmolol are reasonable options. Although intravenous calcium was once recommended, it is now contraindicated because it may enhance neurotransmitter release. There is currently one antivenom approved for the treatment of native widow spiders. Indications for the Merck antivenom include pain that persists despite appropriately dosed analgesics and muscle relaxants. Antivenom should also be considered in patients at high risk for complications from uncontrolled hypertension, such as pregnant individuals and patients with coronary artery disease, hypertension, or a history of cerebrovascular accident. One vial should be diluted in 50 mL of normal saline and administered intravenously over 15 minutes. Symptoms should improve significantly within one hour. Although some clinicians may be reluctant to use whole IgG antivenom, only 13 (3.5%) of 374 patients treated with the Merck product had adverse events. 86 A randomized clinical trial of a new F(ab) 2 antivenom demonstrated faster and more complete symptomatic relief when compared to placebo in patients also receiving supportive care. 87 There were no deaths or serious adverse events. The product is not available at the time of this writing but may be on the market in late 2023. There are a number of treatments that should be avoided in widow spider envenomation. As with snakebites, there is no role for any type of tourniquet, constrictive bandage, incision, or electrical therapy. Because the incidence of infection following widow spider bite is low, antibiotics should not be administered prophylactically. There is also no role for surgical intervention.
Source: Ashley Wahlberg The bite may go unnoticed or feel like a tiny pinprick, but pain will develop within the first hour. Signs and symptoms of widow spider bites include localized pain, redness, and mild swelling. 81 There may be some localized diaphoresis. There is no tissue damage, and small fang marks may or may not be visible. Progressive muscle spasms and cramping of large muscle groups can occur and are typically exquisitely painful. This hypertoxic myopathic syndrome tends to affect the same half (i.e., upper or lower) of the body on which the bite is sustained. Other clinical features may include tachycardia, hypertension, hyperthermia, headache, nausea, vomiting, sweating, weakness, and p avor mortis , the sensation of imminent death. Myocardial ischemia and infarction, cardiomyopathy, priapism, rhabdomyolysis, ileus,
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